Long-term Investment (Details)		1 Months Ended	3 Months Ended	5 Months Ended	6 Months Ended		7 Months Ended
	Jun. 09, 2017 USD ($) $ / shares shares	Jun. 30, 2017 $ / shares	Jun. 30, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($) director $ / shares shares	Jun. 30, 2017 USD ($) $ / shares	Jun. 30, 2016 USD ($)	Dec. 31, 2020 trading_days $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Jun. 09, 2022	Jun. 09, 2020
Schedule of Equity Method Investments [Line Items]
Investment in convertible preferred stock | $					$ 172,500,000	$ 0
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001		$ 0.001
Pandora
Schedule of Equity Method Investments [Line Items]
Investment in convertible preferred stock | $	$ 172,500,000
Dividend income from investment | $			$ 604,000		$ 604,000
Gain (loss) on investment | $			$ 0		$ 0
Pandora | Forecast
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage				19.00%				19.00%
Ownership percentage on an as-converted basis				16.00%				16.00%
Investment in convertible preferred stock | $				$ 307,500,000				$ 480,000,000
Number of directors designated | director				3
Minimum ownership percentage for director designation				50.00%				50.00%
Director designation period				2 years
Minimum ownership percentage for designation of two directors				75.00%				75.00%
Pandora | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001
Preferred stock dividend rate, percentage		6.00%
Pandora | Series A Preferred Stock | Forecast
Schedule of Equity Method Investments [Line Items]
Price per share (in dollars per share) | $ / shares				$ 10.50				$ 10.50
Common shares issued upon conversion (in shares) | shares				95.2381				95.2381
Mandatory redemption period				5 years
Percentage of liquidation preference				100.00%				100.00%	100.00%	100.00%
Convertible preferred stock, stock trigger price | $ / shares							$ 18.375
Convertible preferred stock, threshold trading days | trading_days							20
Convertible preferred stock, threshold consecutive trading days | trading_days							30
Pandora | Series A Preferred Stock | Forecast | Minimum
Schedule of Equity Method Investments [Line Items]
Mandatory redemption period				3 years
Pandora | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Price per share (in dollars per share) | $ / shares	$ 1,000
Pandora | Series A Preferred Stock | Forecast
Schedule of Equity Method Investments [Line Items]
Number of shares issued (in shares) | shares				307,500				480,000
Pandora | Pandora | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Number of shares issued (in shares) | shares	172,500